People tend to think of comic books as a genre, but they’re not–comic books are a medium, a form of storytelling in which words and pictures come together to create a reading experience as rich and rewarding as any other.

Superheroes may represent the majority of mainstream comic books, but the medium is home to as many genres as both the novel and nonfiction.

Despite counting millions of adults among its readership at the medium’s peak in the 1950s, comic books have long been thought of as only for children. That changed in the 1970s and 80s with the advent of the graphic novel.

What’s the difference between comic books and graphic novels? Books like Will Eisner’s A Contract with God and Art Spiegelman’s Maus diverged artistically and thematically from mainstream comics, exploring topics like spirituality and the Holocaust in stark black and white. These were actual books with spines, not stapled monthly magazines, and they were free from ads for sea monkeys and x-ray specs.

In recent years, books like Alison Bechdel’s Fun Home and Marjane Satrapi’s Persepolis have earned accolades for chronicling personal, social, and political upheaval around the world, and they’ve done it in graphic novels.

John Lewis’ March is an excellent addition to this list, a book whose powerful message transcends all mediums.